In the industry of wellbore construction for the exploitation of hydrocarbon fluid from earth formations, expandable tubular elements find increasing application. A main advantage of expandable tubular elements in wellbores relates to the increased available internal diameter downhole for fluid production or for the passage of tools, compared to conventional wellbores with a nested casing scheme. Generally, an expandable tubular element is installed by lowering the unexpanded tubular element into the wellbore, whereafter an expander is pushed, pumped or pulled through the tubular element. The expansion ratio, being the ratio of the diameter after expansion to the diameter before expansion, is determined by the effective diameter of the expander.
In some applications it is desirable to apply a structure which is locally expanded to a diameter larger than the final diameter as determined by the expansion ratio of the tubular element. Such locally increased expansion diameter can be desired, for example, to create a packer around the expandable tubular element, to create an anchor for anchoring the expanded tubular element to the surrounding rock formation, or to release a triggering fluid. Accordingly there is a need for an expandable tubular element system which provides a locally increased expansion diameter relative to the overall expansion ratio of the tubular element.